JPH03182063A - Deteriorated condition sensing method for sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To sense accurately deterioration of a pos. electrode lattice originating from elongation and/or corrosion and also deterioration resulting from decrease of electrolyte by arranging a specified deterioration sensing electrode, and sensing the impedance between this sensor electrode and the pos. or neg. electrode. CONSTITUTION:A deterioration sensing electrode 7 is arranged so as to contact the electrolyte alongside an electrolyte retaining body 8 and move apart from a pos. electrode plate 4 and a neg. electrode plate 3. No.1 AC current and No.2 AC current having different frequencies are impressed between a pos. electrode terminal Tb and a neg. electrode terminal Ta, and the impedance between specified electrodes is measured at an electrode terminal Tc for sensing, and the change therein gives precision sensing of the deteriorated condition of the battery. That is, the value obtained by subtracting the impedance between the pos. and neg. electrodes in No.1 AC current from the impedance between the pos. electrode and the sensor electrode in No.2 AC current gives deterioration of the pos. electrode lattice, while the impedance change between the pos. and neg. electrodes in the No.1 AC current gives the degree of decrease in the electrolytic solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the deterioration state of a sealed lead-acid battery in which gas absorption occurs at the cathode.

[Prior Art] In recent years, sealed lead-acid batteries have come to be used for various purposes. For example, it is also used as an emergency power source for uninterruptible power supplies. However, since a sealed lead-acid battery is a sealed type, it is not possible to open the liquid spout and see inside the battery, unlike a typical lead-acid battery. As a result, it is not possible to measure the specific gravity of the electrolyte to detect the deterioration state (life span) of the battery, and the electrolyte decreases due to moisture permeation, which causes the deterioration of sealed lead-acid batteries, and the expansion and corrosion of the anode grid. Or the degree of expansion cannot be easily determined.

Therefore, various methods have been proposed to detect the deterioration state of sealed lead-acid batteries.

The decrease in the electrolyte due to moisture permeation can be detected by measuring the internal resistance of the battery with a mΩ meter or the like. This is because the adhesion between the electrode plate and the separator deteriorates due to a decrease in the electrolyte, resulting in an increase in internal resistance. Further, the elongation of the anode grid can be detected by using a technique in which a magnetic body is fixed to a pole plate and the position of the magnetic body is detected from outside the battery case.

However, when measuring the internal resistance of a battery with a mΩ meter or the like, the amount of change in internal resistance is small and the measurement accuracy is not necessarily high. Furthermore, detecting the elongation of the anode grid using a magnetic material or the like requires special pole plates, magnetic detection elements, etc., which increases the price of the battery.

Therefore, the inventors of the present application have discovered that the deterioration state of a sealed lead-acid battery can be detected by detecting a large internal resistance of a battery, and by determining elongation and corrosion of the anode grid from changes in the battery's internal resistance. We proposed a method that can detect with high accuracy (Japanese Patent Application No. 6379586). In this method, the frequency of the alternating current component is increased by 100 when the electrolyte is decreasing.
A large increase in internal resistance (internal impedance) is observed when the frequency is increased above Hz, and a large change in internal resistance is observed when the frequency of the alternating current component is reduced to less than 100 Hz when the anode lattice has progressed to elongation or corrosion. The state of deterioration is detected based on the

[Problems to be Solved by the Invention] However, in the method previously proposed by the inventors, it could not be said that the accuracy of detecting the state of deterioration due to corrosion of the anode grid was not necessarily high. Figures 7 and 8 show that the rated capacity is 1.
An accelerated life test was conducted at high temperature using a sealed lead-acid battery with a rated voltage of 2V and 2Ah, and the results were measured using the method proposed earlier. FIG. 7 shows an example of changes in discharge capacity and internal impedance when the electrolytic solution is intentionally reduced without water replenishment. In this example, an alternating current was passed between the anode and the cathode, and the frequency was I, KHz. Furthermore, FIG. 8 shows an example of changes in discharge capacity and internal impedance when water is replenished at regular intervals to intentionally cause elongation and corrosion of the anode grid. In this example, the frequency of the alternating current is 1
It was set to 0Hz. Note that in FIGS. 7 and 8, the internal impedance is shown with the initial value of measurement set to 1.

As can be seen from Fig. 7, the internal impedance increases to nearly four times the initial internal impedance when the capacity becomes 50% of the rated capacity due to deterioration due to a decrease in electrolyte, whereas the internal impedance increases to nearly four times the initial internal impedance. As can be seen from the figure, the internal impedance increases by only about twice the initial internal impedance when the capacity reaches 50% due to deterioration due to elongation and corrosion of the anode grid. Therefore, in the method proposed earlier,
There has been a problem in that the accuracy of detecting deterioration due to elongation and corrosion of the anode grid is lower than the accuracy of detecting deterioration due to decrease in electrolyte.

An object of the present invention is to provide a method for detecting a deterioration state of a sealed lead-acid battery, which can improve the accuracy of detecting deterioration due to elongation and corrosion of an anode grid.

Another object of the present invention is to detect the deterioration state of a sealed lead-acid battery by increasing the accuracy of detecting deterioration due to elongation and corrosion of the anode grid, and at the same time detecting deterioration due to decrease in electrolyte. The purpose is to provide a method.

[Means for Solving the Problem] The present invention provides a sealed lead-acid battery by passing a current containing an alternating current component between an anode and a cathode, and measuring impedance from the alternating current voltage component between predetermined electrodes. The subject is a method for detecting the deterioration state of.

In the invention described in each claim, the deterioration detection electrode is characterized by being in contact with the electrolytic solution and not in contact with the anode and the cathode.In the invention of claim 1, a charging/discharging reaction occurs between the anode and the cathode. In the invention of claim 2, the impedance between the anode and the deterioration detection electrode is measured by passing a current containing an alternating current component at a frequency of In order to improve the detection accuracy of the deterioration state and also detect deterioration caused by a decrease in the electrolyte, an alternating current component of a first frequency that does not substantially cause a charge/discharge reaction between the anode and the cathode is provided. A second frequency alternating current that measures the impedance between the anode and the cathode and between the anode and the deterioration detection electrode by passing a current containing the current, and also causes a charge/discharge reaction between the anode and the cathode. A current containing a current component is applied to measure the impedance between the anode and the deterioration detection electrode. Deterioration of the battery due to a decrease in electrolyte is detected based on changes in impedance between the anode and cathode. Also, the impedance between the anode and the deterioration detection electrode when a current containing an alternating current component of the second frequency is passed, and the anode and the deterioration when a current containing an alternating current component of the second frequency is passed. The deterioration state of the anode is detected based on the change in the impedance difference between the anode and the detection electrode.

The deterioration detection electrode detects an alternating voltage component included in the potential of the electrolytic solution with respect to the anode or cathode when a current containing an alternating current component is passed between the anode and the cathode. In a sealed lead-acid battery, the electrolyte is held in the electrolyte holder, so by attaching the deterioration detection electrode to the electrolyte holder, the deterioration detection electrode can be brought into contact with the electrolyte. By arranging the deterioration detection electrode at the bottom or side of the electrode plate group via the electrolyte holder, it is possible to reliably prevent a short circuit between the deterioration detection electrode and the anode or cathode.

Note that the deterioration detection electrode may be any electrode as long as it has acid resistance.

The current containing an alternating current component that flows through the anode and the cathode may be only an alternating current, or may be one in which alternating current is superimposed on a charging direct current.

[Function] Lead-acid batteries have the following components: anode, electrolyte, and cathode, and the impedance between the anode and cathode is determined by the anode active material.
It includes the interfacial impedance at the electrolyte interface, the interfacial impedance at the cathode active material-electrolyte interface, the resistance of the electrolyte itself (electrolyte resistance), and the resistance of each electrode plate. The interfacial impedance changes depending on the frequency of the alternating current component passed between the electrodes, and in the case of lead-acid batteries, the interfacial impedance generally increases as the frequency decreases. This is because when the frequency of the alternating current component is high, the charge/discharge reaction between the active material and the electrolyte cannot catch up and virtually no charge/discharge reaction occurs, whereas when the frequency is low, the charge/discharge reaction does not occur. This is because impedance due to charging and discharging reactions increases.

It is thought that the interfacial impedance naturally increases when the electrode plate deteriorates because charge/discharge reactions become difficult to occur, and when the anode lattice corrodes or stretches, the interfacial impedance between the anode active material and the electrolyte increases. is expected to increase. As a result, when the electrode plates deteriorate, the impedance between the anode and cathode of the lead-acid battery increases. As mentioned above,
In the prior invention, the deterioration of the anode is detected from the change in the impedance between the anode and the cathode, using the frequency of the alternating current component as the frequency at which the charge/discharge reaction occurs. The rate was not necessarily large, and the detection accuracy was poor. As a result of the inventor's research, it was found that the rate of increase in the interfacial impedance between the anode active material and the electrolyte is greater than the rate of increase in the impedance between the anode and the cathode when the anode deteriorates.

Therefore, in the present invention, in order to detect the deterioration state of the anode, the deterioration detection electrode is placed in contact with the electrolytic solution and not in contact with the anode and the cathode, and a charge/discharge reaction is caused between the anode and the cathode. By passing a current containing an alternating current component of the frequency, changes in the interfacial impedance between the anode active material and the electrolyte are directly detected. As a result, in the present invention, it has become possible to accurately detect the deterioration state of the anode, which has deteriorated due to elongation and corrosion of the anode grid.

The impedance between the electrolyte (deterioration detection electrode) and the anode is not the same as the interfacial impedance between the electrolyte and the anode active material. That is, the measured value of the impedance between the anode and the detection electrode includes the interfacial impedance between the deterioration detection electrode and the electrolyte, the electrolyte resistance, and the resistance needle of the anode itself.

By excluding these impedances from the measured values, changes in the interfacial impedance between the anode active material and the electrolyte can be measured with higher accuracy.

Therefore, in the invention of claim 2, the difference between the anode and the deterioration detection electrode when a current containing an alternating current component with a frequency that does not substantially cause a charge/discharge reaction is passed between the anode and the cathode. The impedance (hereinafter this impedance is referred to as non-interface impedance) is measured, and the anode and the deterioration occur when a current containing an alternating current component at a frequency that causes a charge/discharge reaction is passed between the anode and the cathode. The difference in impedance between the anode and the detection electrode is determined, and deterioration of the anode is detected based on this impedance difference. Therefore, according to the second aspect of the present invention, it is possible to detect an increase in interfacial impedance that is substantially caused by a charge/discharge reaction, so that the accuracy of detecting deterioration of the anode can be further improved.

Furthermore, when a current containing an alternating current component at a frequency that does not substantially cause charge/discharge reactions is passed between the anode and the cathode, both the anode active material-electrolyte interface and the cathode active material-electrolyte interface Since the interfacial impedance caused by charge/discharge reactions on the slope is small, the impedance between the anode and the cathode is dominated by the aforementioned non-interfacial impedance including electrolyte resistance. In particular, the electrolyte resistance changes as the electrolyte increases or decreases, so the impedance between the anode and the cathode is largely controlled by the electrolyte resistance. Therefore, the impedance value measured between the anode and the cathode can be used to evaluate the degree of deterioration due to decrease in electrolyte. Note that this point is the same as the invention of the earlier application.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a sealed lead-acid battery used in an embodiment of the method of the present invention. In the figure, ■ is a battery case, and 2 is an electrode plate group formed by laminating an anode plate 3 and a cathode plate 4 with an electrolyte holder 5 in between.

A deterioration detection electrode 7 is arranged between the lower part of the electrode plate group 2 and the inner wall surface of the battery case 1 with an electrolyte holder 8 interposed therebetween. In this example, the deterioration detection electrode 7 is arranged at the bottom of the electrode plate group 2, but the electrode may be arranged between the side of the electrode plate group and the inner wall surface of the battery case. The deterioration detection electrode 7 may be any electrode that has acid resistance, but in this embodiment, a cut piece of a small sealed lead acid battery anode plate is used as the deterioration detection electrode 7. In addition, in FIG. 1, the electrode 7 and the battery case 1 are
Although there is a gap between the electrode 7 and the inner wall surface of the electrode 7, in reality, the electrode 7
In order to sufficiently contact the electrolyte in the electrolyte holder 8, the two are brought into close contact with each other. Naturally, there is actually no gap between the electrode plate group 2 and the inner wall surface of the battery case 1. In Figure 1, T
a is a cathode terminal, Tb is an anode terminal, and Tc is a deterioration detection electrode terminal.

The battery used in the test had the above configuration and a rated voltage of 2V.

It is a sealed lead-acid battery with a rated capacity of 1.2 Ah, and was evaluated through an accelerated life test at high temperatures.

FIG. 2 shows a schematic configuration of an example of an impedance measuring device used to implement the method of the present invention. This measuring device measures the frequency of the alternating current component of the flowing current.
This measures the impedance between each terminal of the battery 10 in the case of IKHz and IHz. Therefore, a first oscillator 11 that generates a signal voltage with a frequency of IKHz and a second oscillator 12 that generates a signal voltage with a frequency of IH2 are provided. Of course, the frequency may be changed using a single variable frequency oscillator. The outputs of the first and second oscillators 11 and 12 are input to the voltage-current converter 14 via the changeover switch 13. The voltage-current converter 14 converts the signal voltages output from the oscillators 11 and 12 into alternating currents of the same frequency. The alternating current output from the voltage-current converter 14 is applied between the anode terminal Ta and the cathode terminal Tb of the battery under test 10.

Figure 2 shows the connection state when measuring the impedance between the anode terminal Tb and the detection electrode terminal Tc.
The ten input terminals of the differential amplifier 15 are connected to the anode terminal Tb, and the other input terminal is connected to the detection electrode terminal Tc. Differential amplifier 15 detects an AC voltage component generated between anode terminal Tb and detection electrode terminal Tc, and outputs it to AC voltage amplifier 16 . The AC voltage amplifier 16 amplifies the detected AC voltage component by a predetermined amplification factor and outputs the amplified AC voltage component to the AC voltage detection section F. The AC voltage detection unit 17 outputs a DC voltage proportional to the value from the peak to the peak of the amplitude of the AC voltage output from the amplifier ↓6. The AC voltage detection section 17 can be configured using, for example, a commercially available peak 10 peak measurement module. The DC voltage output from the AC voltage detection section F is displayed on the digital voltmeter (8).

Since the effective value of the alternating current output from the voltage-current converter 14 and the amplification factor of the amplifier 16 are known in advance, by dividing the output of the digital voltmeter 18 by these values, the difference between the anode and the deterioration detection electrode can be calculated. The absolute value of impedance is obtained.

Further, when measuring the impedance between the anode and the cathode, the second input terminal of the differential amplifier 11 may be connected to the anode terminal Tb and the cathode terminal Ta of the battery under test 10.

Note that the method for measuring the impedance between each terminal is not limited to the case where the above device is used, and a known method for measuring impedance can be used.

The results of measuring the impedance between the anode and the cathode and the impedance between the anode and the detection electrode using the above-described sealed lead-acid battery and the impedance measuring device are shown in FIGS. 3 and 4. Figure 3 shows the results of the anode-electrode test in a high-temperature accelerated life test when the frequency of the alternating current component was set at IKHz and the battery 10 was brought to the end of its life by reducing the electrolyte without replenishing water.
It shows the relationship between cathode-to-cathode impedance (internal impedance) and discharge capacity. As shown in FIG. 3, when the capacity decreased to 50% of the rated capacity, the internal impedance increased to about four times the initial value.

Figure 4 shows the relationship between the interfacial impedance between the anode and the electrolyte and the discharge capacity in a high-temperature accelerated life test in which water is periodically replenished at a frequency of IHz and the battery reaches its end of life due to corrosion and elongation of the anode grid. FIG. 3 is a characteristic diagram showing the relationship. Here, the interfacial impedance between the anode and the electrolyte is a value obtained by subtracting the impedance between the anode and the cathode at the frequency IKHz from the impedance between the anode and the detection electrode at the frequency IHz. As shown in FIG. 4, when the capacity has decreased to 50% of the rated capacity, the interfacial impedance has increased to about four times the initial value. As described above, according to this example, even when the life is reached due to a decrease in the electrolyte solution or when the life is reached due to corrosion and elongation of the anode grid, the rate of increase in impedance changes by about 4 times. Battery deterioration could be detected with high accuracy.

Figure 5 also shows the results of an anode life test in a high temperature accelerated life test where the frequency of the alternating current component was IHz and periodic water replenishment brought the battery to the end of its life due to corrosion and elongation of the anode grid.
It shows the relationship between impedance between detection electrodes and discharge capacity. 50% of the rated capacity as shown in Figure 5.
At the point when the capacitance has decreased to 1, the impedance has increased to about three times the initial value. Although the rate of increase in impedance is small compared to the rate of increase in interfacial impedance shown in Figure 4, the rate of increase in impedance is large compared to the results shown in the conventional measurement method shown in Figure 8. Deterioration detection accuracy can be improved.

Figure 6 shows the frequency dependence of the interfacial impedance between the anode and electrolyte of sealed lead-acid battery B, which reached the end of its life due to corrosion and elongation of the anode grid during a high-temperature accelerated life test, and the frequency dependence of the interfacial impedance between the anode and electrolyte of sealed lead-acid battery A, which was new. The frequency dependence of the interfacial impedance between the anode and the electrolyte is shown. The battery used to obtain the data had a structure similar to that shown in the figure, and had a rated capacity of 1.2 Ah and a rated voltage of 2V. Note that cadmium wire (
Measurements were carried out by using a cadmium wire formed into a wire shape and bringing the cadmium wire into contact with an electrolyte holder. FIG. 6 shows the relationship between the frequency of the alternating current component and the interface impedance. Measurement of interfacial impedance is performed at a frequency of 1KH.
It is the value obtained by subtracting the impedance at z from the measured impedance at each frequency. As shown in Figure 6, the difference in interfacial impedance between battery B, which has reached the end of its life, and battery A, which is new, becomes large from frequencies below about 100 Hz.
A difference of about 4 times was observed in the IHz frequency.

In the above embodiments, measurements were made by passing an alternating current between the anode and the cathode, but measurements can also be made by passing a current containing an alternating current component between the anode and the cathode.

Therefore, even during trickle or float charging, the measurement according to the present invention is possible as long as an alternating current can be passed between the anode and the cathode. FIG. 9 shows an example of the configuration of a charger that can superimpose an alternating current component on a charging current.

In the figure, 20 is a DC power supply, 21 is a transistor, 2
2 is a current detection resistor, 23 is an error amplifier, 24 is an adder, 25 is a reference power source, 26 and 27 are first and second oscillators, 28 is a changeover switch, and 29 is a ground terminal.

The first oscillator 26 is an oscillator that generates a sine wave signal with a frequency of IKHz, and the second oscillator 27 is an oscillator that generates a sine wave signal with a frequency of IHz. The adder 24 adds the voltage signal input through the changeover switch 28 to the voltage of the reference power supply 25, and adds the voltage signal input through the changeover switch 28 to the voltage of the reference power supply 25.
3 performs feedback control of the output by controlling the base current of the transistor 2↓.

When performing normal charging, the selector switch 28 is connected to the ground terminal 29, and the reference voltage of the reference power supply 25 is input from the adder 24 to the error amplifier 23. The error amplifier 23 controls the transistor 22 based on the reference voltage of the reference power supply 25, and performs constant voltage control. When a current containing an alternating current component is applied to measure impedance, the changeover switch 28 is connected to the first or second oscillator 26 or 27. Adder 24 adds the output voltage of oscillator 26 or 27 to the reference voltage of reference power supply 25 and outputs the result to error amplifier 23 . The error amplifier 23 is connected to the oscillator 26
Alternatively, by varying the base current of the transistor 21 according to changes in the frequency and amplitude of the output of the transistor 27, an alternating current component is superimposed on the charging current.

[Effect of the invention] According to the claimed invention, in order to detect the deterioration state of the anode, the deterioration detection electrode is arranged so as to be in contact with the electrolyte and not in contact with the anode and the cathode. Changes in interfacial impedance between the anode active material and the electrolyte are directly detected by passing a current containing an alternating current component at a frequency that causes a charge/discharge reaction between the anode grid and The deterioration state of the anode, which has deteriorated due to body elongation and corrosion, can be detected with high accuracy.

Further, according to the invention of claim 2, when a current containing an alternating current component with a frequency that does not substantially cause a charge/discharge reaction is passed between the anode and the cathode, the deterioration detection electrode is The difference between this impedance and the impedance between the anode and the deterioration detection electrode when a current containing an alternating current component with a frequency that causes a charge/discharge reaction is passed between the anode and the cathode. Since the deterioration of the anode is detected based on the difference in impedance, it is possible to detect the increase in interfacial impedance caused by the charge/discharge reaction, which improves the accuracy of detecting deterioration of the anode. It can be further increased. It also has the advantage of being able to detect battery deterioration due to a decrease in electrolyte with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of a battery for implementing the method of the present invention, FIG. 2 is a block diagram showing an example of an impedance measuring device used when implementing the method of the present invention, and FIG. The figure is a characteristic diagram showing the relationship between the anode-cathode impedance and discharge capacity when the frequency of the alternating current component is IKHz when the electrolyte is reduced without water replenishment to bring the battery to the end of its life. Figure 5 is a characteristic diagram showing the relationship between the interfacial impedance between the anode and the electrolyte and the discharge capacity at a frequency of ↓ Hz when the battery is brought to the end of its life due to corrosion and elongation of the anode grid by water replenishment. Figure 6 is a characteristic diagram showing the relationship between the impedance between the anode and the deterioration detection electrode and the discharge capacity at a frequency of IHz when the battery is brought to the end of its service life due to corrosion and elongation of the anode grid by water replenishment. Frequency dependence of the interfacial impedance between the anode and the electrolyte of a sealed lead-acid battery whose life has come to an end due to corrosion and elongation of the anode grid in an accelerated life test, and the anode of a new sealed lead-acid battery.
A characteristic diagram showing the frequency dependence of the interfacial impedance between electrolytes, Figure 7 shows that the frequency measured using the conventional method is IKH.
Figure 8 is a characteristic diagram showing the relationship between anode-cathode impedance and discharge capacity at a frequency of 10 Hz measured using a conventional method. , FIG. 9 is a block diagram showing an example of a charging device that superimposes an alternating current component on a charging current. 1... Battery case, 2... Electrode plate group, 3... Cathode plate, 4...
...Anode plate, 5, 8... Electrolyte holder, 7... Deterioration detection electrode, 10... Battery to be measured, 11.12...
・Oscillator, 13... Selector switch, 14... Voltage -
Current converter, 15 differential amplifier, 16... AC voltage amplifier, 17... AC voltage detector, 18... digital voltmeter, 20... DC power supply, 21... transistor,
22... Resistor, 23... Error amplifier, 24... Adder, 25... Reference voltage, 26.27... Oscillator,
28... Selector switch. Fig. Fig. Fig. Fig. Fig. Discharge capacity (Rating: 100) Fig. Discharge capacity (Rating: 100> Fig. Fig. Fig. Fig. 5 Frequency (H2) Fig. Fig. Fig.

Claims (2)

[Claims] (1) A method of detecting the deterioration state of a sealed lead-acid battery by passing a current containing an alternating current component between the anode and the cathode and measuring the impedance from the alternating current component between the predetermined electrodes. A deterioration detection electrode is placed in contact with the liquid and not in contact with the anode and cathode, and a current containing an alternating current component at a frequency that causes a charge/discharge reaction to occur between the anode and cathode is applied. A method for detecting a deterioration state of a sealed lead-acid battery, comprising: measuring impedance between the anode and the deterioration detection electrode, and detecting a deterioration state of the anode based on a change in the impedance. (2) In a method of detecting the deterioration state of a sealed lead-acid battery by passing a current containing an alternating current component between the anode and the cathode and measuring the impedance from the alternating current voltage component between the predetermined electrodes, electrolysis A deterioration detection electrode is placed in contact with the liquid and not in contact with the anode and cathode, and an alternating current of a first frequency that does not substantially cause a charge/discharge reaction between the anode and the cathode. measuring the impedance between the anode and the cathode and the impedance between the anode and the deterioration detection electrode by passing a current containing the component, and causing a charge/discharge reaction between the anode and the cathode. measuring the impedance between the anode and the deterioration detection electrode by passing a current containing an alternating current component at a second frequency, and measuring the impedance between the anode and the cathode based on the change in impedance between the anode and the cathode, impedance between the anode and the deterioration detection electrode and the alternating current component of the second frequency when a current containing an alternating current component of the first frequency is applied. Detection of a deterioration state of a sealed lead-acid battery, characterized in that the deterioration state of the anode is detected based on a change in impedance difference between the anode and a deterioration detection electrode when a current containing the current is applied. Method.